.Caseyville police officer Chris Singleton walks past as his canine companion, Paco, a male German shepherd, pauses on this climbing structure during the agility testing at the Region 16 USPCA (United States Police Canine Association) field trials. The trials are being held this weekend in O'Fallon, and are hosted by the O'Fallon police department. Each dog is graded for their ability as they run up, over and through the various structures, which were set up in a field adjacent to the O'Fallon police station on Seven Hills Road..